1. Field of the Invention
The present invention relates to a saw having a light source alignment system that does not require internal batteries to power the light source.
2. Background Art
Miter saws, portable circular saws, radial arm saws, chop saws, and compound saws are used to precisely cut wood and other materials. For example, miter saws and compound saws are used to cut baseboards, crown moldings, cove moldings, and a wide variety of trim pieces and structural members to exact dimensions. Such circular saws generally have a blade that is rotated at a high rate of speed to cut workpieces. The blade is guarded by a retractable blade guard that covers the saw blade but is retracted as the blade is brought into contact with a workpiece. The workpiece is retained on a base and a turntable that, in conjunction with a fence, are used to position the workpiece to be cut by the saw.
Before cutting, workpieces are generally marked with a pencil at the intended cut location according to precise measurements to assure accuracy. A common problem with these types of saws is that it takes considerable skill and attention to consistently align the workpiece with the saw blade so that the edge of the saw blade cuts the workpiece at the desired location. With prior art saws, it has not been possible to know if the saw alignment is proper until the saw begins to cut the material. The workpiece may be ruined if it is not set up at the correct orientation when the saw blade contacts the workpiece.
A laser arbor for a circular saw has been proposed in U.S. Pat. No. 5,862,727 to Kelly. The Kelly patent discloses the use of a semiconductor laser arbor for a circular saw that is actuated by a centrifugal switch and directs a line of laser beam on a workpiece. The Kelly patent discloses a battery powered laser light source. One problem with reliance upon batteries is that the semiconductor laser light source draws substantial power from the batteries to illuminate the laser, resulting in limited battery life and requiring frequent battery changes. Similarly, U.S. Pat. No. 6,035,757 to Caluori et al. discloses a similar semiconductor laser light beam alignment device for a circular saw having a focusing lens that causes the laser beam to be directed to the blade cut line. The Caluori patent likewise relies upon a battery power source that is carried by the laser arbor. This system has the same problem of limited battery life as the Kelly patent.
The assignee of this application has marketed a battery power laser alignment device which is described in copending U.S. patent application Ser. No. 09/860,898 entitled “Miter Saw Having a Light Beam Alignment System” which is incorporated by reference herein for general background purposes.
Applicants have solved the battery life problem by their development of a laser alignment system that utilizes a power source external to the laser arbor.